Recently, since the mobile wireless communication and the wireless LAN have being widely used, a large market of wireless note books, personal digital assistants and portable computers are developed rapidly therefore.
However an antenna will be necessary for any kind of those products for radiating and receiving electronic waves, therefore a designation of an antenna will directly effect the efficiency of the wireless transmission, furthermore, for a portable wireless device the size of an antenna should be reduced, therefore a plate type concealed antenna is used instead of the conventional exposed antenna, and it has a grounded surface of an upside of the plate type antenna to shield interference waves therefor, and further, it provides a better outside looking.
There are two different frequency channels used generally in time now with the specification according to item 802.11a and 802.11b of the wireless LAN standard established by IEEE, which item 802.11a specified a channel of 5.2 GHZ, while item 802.11b specified a channel of 2.4 GHZ. The channel of 5.2 GHZ provides a higher safety but a shorter transmitting distance in compare with the channel of 2.4 GHZ, therefore a wireless transmitting product has to change another antenna while the product needs to change another channel for transmission, it is inconvenient.
There is a problem of how to use one antenna to fit two different channels, which confuses antenna producers, the inventor of the present invention has been solved aforesaid problem under a long time research and practical test to design a plate type antenna.
Therefore, an object of the present invention is to provide a plate type antenna with dual channels that can be simultaneously used on two specified channels of wireless LAN standard of IEEE. Convenient to use to avoid the trouble of antenna changing.
Another object of the present invention is to provide a plate type antenna with dual channels for reducing the cost of production.